India extend between 68°7′ E to 97° 25′ E longitudes. The East-West extent is 2933 km. which is roughly l/12th of the circumference of the earth. Thus, India has a longitudinal extent of about 30° longitudes. There is a time lag of 2 hours between the sunrise in the easternmost and the westernmost horizons of India. It means that the sun takes two hours to rise in Saurashtra after it has region in Arunachal Pradesh. There is a difference of 4 minutes for 1° of longitude. Therefore, there is difference of time of 2 hours (30° × 4 = 120 minutes = 2 hours). It has been suggested to have two standard meridians (instead of one) to reduce time lag to 1 hour.
